Ostraka

Ostraka,
plural of the Greek term ostrakon, "potsherd" or "fragment," were flakes of
limestone found in abundance in the cliffs of western Thebes. The high price
of papyrus and the ready availability of ostraka made them a popular writing
surface for both scribes and artists. Ostraka had a variety of uses, including
scribal and artistic training, work and payment schedules, correspondence, legal
documents, and architectural plans. This ostrakon, on loan from the Semitic
Museum, Harvard University, depicts the god Osiris, and is an example of an
artist's trial sketch.